We might finally have a hint of what Google spent its money on when it acquired Motorola Mobility: a really customizable line of smartphones.

How customizable? Think Legos.

Motorola just announced a new initiative called Project Ara, which the company describes as a "free, open hardware platform for creating highly modular smartphones." The concept aims to do for Android hardware what Android has done for the smartphone OS environment: make the phone itself a modular construction where pieces can be added, removed, swapped out, or upgraded at will.

Another project in this same vein, Phonebloks, must have caught Motorola's attention, because it contacted the creator of that concept, Dave Hakkens, and is working with him attract to Project Ara the attention of folks interested in his project.

Project Ara's approach involves two types of components, a basic skeleton (what Motorola calls an "endo," short for "endoskeleton") and modules that snap into the endo. The modules could theoretically be anything from multiple batteries to additional displays or keyboards. It clearly goes far beyond the ho-hum color-and-finish customization that Motorola offered with the Moto X.

Tough to make...

It doesn't take an EE degree to grok the technical challenges involved in making something this deliberately open-ended. The basic idea of having components that snap into a backplane has been a mainstay of computing for decades, but it's going to be very tough sledding indeed to make it work well on the scale needed for a smartphone. It may not be possible to make the resulting product anywhere as thin as the phones most people are accustomed to, if only because thinness also means fragility.

Motorola's outreach for this project is spanning multiple domains. The company is inviting people worldwide to become what it calls "Ara Scouts," folks who can work as a street team for the project and get the word out to people -- including those who don't already have a smartphone "or a phone at all." This implies Motorola is aiming at markets that haven't had smartphone penetration yet and where the "Nokia brick" form factor is still the standard.

Motorola has actually been beating the drum for this project longer than most people realize. Back in March, Motorola adviser Guy Kawasaki posted on Google+ how great it would be if a phone could be customized like a Porsche Exclusive. To a degree, we already do this -- via add-on Bluetooth-connected hardware, cases, and software -- but Motorola's talking about a level of customization that might be intimidating to most users.

... and maybe just as tough to market

Part of the popularity of the iPhone lies in its simplicity. Apple keeps few iterations of the product on the market at any given time, because it knows after a certain point a wider range of choices becomes counterproductive (aka the "paradox of choice"). Project Ara might face major hurdles with regular users for the same reason: Do most people really want to be forced to make that many choices about the construction of their phone?

Maybe not out of the gate. One possible scenario is that users could purchase one of a number of basic pre-assembled Ara models, then enjoy the freedom to customize it later -- and in the long run enjoy more customization and more longevity of the product than most any Apple user.

Project Ara might never displace Apple, the way Android hasn't really displaced Apple but instead consolidated the respective niches for each product family. But Ara would be one heck of an alternative -- and not just to Apple, but to the phone world as we currently know it.